Does texture baking use the GPU or CPU?
Blender currently comes with two render engines: Blender Render and Cycles. You can switch between them in the top toolbar, in the field farthest to the right. If you haven't touched it, it says 'Blender Render'.



In Blender Render, you can't choose between the CPU and GPU for rendering, it will detect what's available and chooses itself. If you install a new graphics card, it will switch to it.

In Cycles, you can set it to use the GPU, or use the CPU, under Render section, at the top of the Render tab in the Properties panel, in the field that says Device